Rational Design of Coumarin-Based Hybridized Local and Charge-Transfer Blue Emitters for Solution-Processed Organic
Qi Xie1,2, Chuanxin Liao1,2, Hongli Liu1,2
1School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|May 16, 2024
Summary
Novel hybridized local and charge-transfer (HLCT) materials were synthesized for efficient blue organic light-emitting diodes (OLEDs). The pPh-6M material demonstrated excellent deep-blue electroluminescence, highlighting its potential for advanced display technologies.
Area of Science:
- Materials Science
- Organic Electronics
- Photophysics
Background:
- Hybridized local and charge-transfer (HLCT) materials utilize singlet and triplet excitons via
- hot excitons
- for highly efficient blue organic light-emitting diodes (OLEDs).
- The balance between charge-transfer (CT) and locally excited (LE) components in singlet and triplet states is crucial for efficient reverse intersystem crossing.
Purpose of the Study:
- To design and synthesize novel donor-acceptor (D-A) type HLCT materials for efficient blue OLEDs.
- To investigate the effect of structural modifications on the CT and LE components and their impact on photophysical properties.
- To evaluate the performance of these materials in solution-processed doped OLED devices.
Main Methods:
- Rational design and synthesis of three novel HLCT materials: pPh-7P, pPh-7M, and pPh-6M, featuring diphenylamine donors and coumarin acceptors.
- Systematic characterization of HLCT properties using photophysical measurements and density functional theory (DFT) calculations.
- Fabrication and testing of solution-processed doped OLEDs utilizing the synthesized materials.
Main Results:
- The synthesized materials (pPh-7P, pPh-7M, pPh-6M) exhibited tunable CT and LE proportions based on structural modifications.
- pPh-6M demonstrated deep-blue electroluminescence with a maximum emission wavelength of 446 nm.
- OLED devices based on pPh-6M achieved a maximum luminance of 8755 cd/m², a maximum current efficiency of 5.83 cd/A, and a maximum external quantum efficiency of 6.54%.
Conclusions:
- The study successfully developed novel HLCT materials for efficient blue OLED applications.
- pPh-6M, with dominant 1LE and 3CT components, exhibited superior OLED performance compared to other synthesized materials.
- Fine-tuning the molecular structure is key to optimizing the photophysical properties and device performance of HLCT materials.
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